1. Field of the Invention
This invention relates to a plasma display device employing a radio frequency, and more particularly to a plasma display panel that is capable of reducing a discharge power of a plasma display panel using a radio frequency and a method of driving the same.
2. Description of the Related Art
Recently, a plasma display panel (PDP) feasible to the fabrication of large-scale panel has been available for a flat panel display device. The PDP includes discharge cells corresponding to color pixels of matrix type and controls a discharge interval of each discharge cell to display a picture. More specifically, after the PDP selected discharge cells to be displayed by an address discharge, it allows a discharge to be maintained in a desired discharge interval at the selected discharge cells. Thus, in the discharge cells, a vacuum ultraviolet ray generated during the sustaining discharge radiates a fluorescent material to emit a visible light. In this case, the PDP controls a discharge sustaining interval, that is, a sustaining discharge frequency of the discharge cells to implement a gray scale required for an image display. As a result, the sustaining discharge frequency becomes an important factor for determining the brightness and a discharge efficiency of the PDP. For the purpose of performing such a sustaining discharge, a sustaining pulse having a frequency of 200 to 300kHz and a width of about 10 to 20xcexcs has been used in the prior art. However, the sustaining discharge is generated only once at a extremely short instant per the sustaining pulse by responding to the sustaining pulse; while it is wasted for a step of forming a wall charge and a step of preparing the next sustaining discharge at the remaining major time. For this reason, the conventional three-electrode, face-discharge, and AC PDP has a problem in that, since a real discharge interval is very short in comparison to the entire discharge interval, the brightness and the discharge efficiency become low.
In order to solve such a problem of low brightness and low discharge efficiency, we has suggested a method of utilizing a radio frequency discharge employing a radio frequency signal of hundreds of MHz as a display discharge. In the case of the radio frequency discharge, electrons perform an oscillating motion by the radio frequency signal to sustain the display discharge in a time interval when the radio frequency signal is being applied. More specifically, when a radio frequency signal with a continuously alternating polarity is applied to any one of the two opposite electrodes, electrons within the discharge space are moved toward one electrode or the other electrode depending on the polarity of the voltage signal. If the polarity of a radio. frequency voltage signal having been applied to the electrode before the electrons arrive at the electrode is changed when electrons are moved into any one electrode, then the electrons has a gradually decelerated movement speed in such a manner to allow their movement direction to be changed toward the opposite electrode. The polarity of the radio frequency voltage signal having been applied to the electrode before the electrons within the discharge space arrive at the electrode is changed as described, so that the electrons make an oscillating motion between the two electrodes. Accordingly, when the radio frequency voltage signal is being applied, the ionization, the excitation and the transition of gas particles are continuously generated without extinction of electrons. The display discharge is sustained during most discharge time, so that the brightness and the discharge efficiency of the PDP can be improved. Such a radio frequency discharge has the same physical characteristic as a positive column in a glow discharge structure.
FIG. 1 and FIG. 2 are a perspective view and a sectional view showing the structure of the above-mentioned radio frequency PDP employing a radio frequency discharge, respectively. In FIG. 1 and FIG. 2, the PDP includes radio frequency electrodes 12 provided on an upper substrate 10, data electrodes 18 and scanning electrodes 22 provided on a lower substrate 16 in such a manner to be perpendicular to each other, and barrier ribs 28 provided between the upper substrate 10 and the lower substrate 16. The radio frequency electrodes 12 apply a radio frequency signal. A first dielectric layer 14 is formed on the upper substrate 10 provided with the radio frequency electrodes 12. The data electrodes 18 apply a data pulse for selecting cells to be displayed. The scanning electrodes 22 are provided in opposition to the radio frequency electrodes 12 in such a manner to be used as opposite electrodes of the radio frequency electrodes 12. Between the data electrodes 18 and the scanning electrodes 22 is provided a second dielectric layer 20 for the charge accumulation and the isolation. On the second dielectric layer 20 provided with the scanning electrodes 22, a third dielectric layer 24 for the charge accumulation and a protective film 26 are sequentially disposed. The barrier ribs 28 shut off an optical interference between the cells. In this case, since a distance between the radio frequency electrode 12 and the scanning electrode 22 is sufficiently assured for the sake of a smooth radio frequency discharge, the barrier ribs 24 are provided at a higher level than those in the existent three-electrode, AC, and face-discharge PDP. Otherwise, the barrier ribs 28 may be formed into a lattice structure closed on every side for each discharge cell so as to isolate the discharge space. This is because it is difficult to isolate a plasma for each cell unlike the existent face discharge due to the opposite discharge generated between the radio frequency electrodes 12 and the scanning electrodes 22. A fluorescent material 30 is coated on the surface of the barrier rib 28 to emit a visible light with an inherent color by a vacuum ultraviolet ray generated during the radio frequency discharge. The discharge space defined by the upper substrate 10, the lower substrate 16 and the barrier ribs 28 is filled with a discharge gas.
In the PDP having the configuration as described above, as shown in FIG. 3, discharge cells 32 are provided at each intersection among the radio frequency electrodes 12, the scanning electrodes 22 and the data electrodes 18. The radio frequency electrodes 12 are arranged in parallel to the scanning electrodes 22, and the data electrodes 18 are arranged in a direction crossing the radio frequency electrodes 12 and the scanning electrodes 22. At a certain discharge cell 32, an address discharge is generated between the data electrode 18 and the scanning electrode 22, and a radio frequency discharge is generated by a radio frequency signal applied to the radio frequency electrode 12.
Specifically, the conventional radio frequency PDP is driven with a drive waveform as shown in FIG. 4. Generally, the PDP implements an image of one frame by a combination of a number of sub-field. Each sub-field is driven with being divided into an address interval and a discharge sustaining interval. In the address interval, a scanning pulse SP is line-sequentially applied to the scanning electrode 22. At the same time, the data electrode 18 is synchronized with the scanning pulse SP to apply a data pulse DP for each scanning line in accordance with a video data. Accordingly, an address discharge is generated by a voltage difference between the data electrode 18 and the scanning electrode 22 at the discharge cells supplied with the data pulse DP. Most electric charge particles produced by the address discharge are accumulated into a shape of wall charge.
After the lapse of such an address interval, a radio frequency signal RF is applied to the radio frequency electrodes 12 in the discharge sustaining interval to continuously generate a radio frequency discharge at the discharge cells at which the address discharge has been generated. This radio frequency discharge is initiated by a triggering pulse TP applied alternately to the data electrodes 18 and the scanning electrodes 22. This is because, since most charged particles produced by the address discharge are accumulated into a wall charge, it is difficult to induce the radio frequency discharge making use of an electron oscillation only by the radio frequency signal RF applied to the radio frequency electrodes 12. Ton other words, the triggering pulse TP is applied to the data electrodes 18 and the scanning electrodes 22 to generate a triggering discharge at the discharge cells at which a wall charge has been formed by the address discharge. More charged particles are activated by the triggering discharge to easily initiate the radio frequency discharge by the radio frequency signal. Also, the triggering discharge uniforms a wall charge amount having a non-uniform distribution at each discharge cell due to a discharge time difference in the address discharge to generate a uniform radio frequency discharge. Electrons having a high relative mobility in the charged particles activated by such a triggering discharge make an oscillation motion within the discharge space by the radio frequency signal. The electrons making an oscillation motion excite a discharge gas to generate a vacuum ultraviolet ray. The vacuum ultraviolet ray radiates the fluorescent material 30 to generate a visible light.
As described above, in the conventional PDP, the radio frequency discharge is generated between the radio frequency electrodes 12 and the scanning electrode arranged in parallel to each other. In this case, a luminous area (A) proportional to an area of the opposite electrode is diffused and widen into the barrier ribs 28 positioned at each side of the discharge cells 32. If the luminous area (A) is widen, however, a discharge power for the radio frequency discharge is more consumed in proportion to the luminous area (A). Also, when the luminous area (A) has been diffused into the barrier ribs 28, a spurious energy is wasted due to electrons absorbed into the barrier ribs 28. Since an energy loss caused by electrons absorbed into the barrier ribs 28 must be compensated in order to maintain the radio frequency discharge, however, a discharge power is more consumed. If a discharge power, that is, a discharge current is increased, then exciting atoms of a discharge gas generating a vacuum ultraviolet at the PDP have a high de-excitation probability due to their collision with electrons to deteriorate the generation efficiency of a vacuum ultraviolet and hence the luminescence efficiency of a fluorescent material. Furthermore, since electrons absorbed into the barrier ribs 28 become abundant from a large luminous area (A) when the conventional radio frequency PDP has a fine structure for the sake of implementing a high resolution to reduce the size of discharge cell, a discharge power must be more increased to that extent so as to obtain an equal brightness.
Moreover, in the conventional radio frequency PDP, since the triggering discharge is generated at the lower part provided with the data electrodes 18 and the scanning electrodes, most charged particles produced by the discharge are concentrated at the vicinity of the lower plate. In other words, the charged particles to be used for the radio frequency discharge are positioned at a relatively distant area from the radio frequency electrodes 12. Accordingly, a higher level of radio frequency signal is required to bring electrons in the charged particles at the lower part into the radio frequency electrodes 12 for the radio frequency discharge, a lot of power is consumed. Otherwise, since a mount of electrons making an oscillation motion has a limit when the radio frequency signal fails to have a level enough to draw the electrons into the radio frequency, the luminescence efficiency is deteriorated.
Accordingly, it is an object of the present invention to provide a radio frequency PDP that is capable of reducing a discharge power as well as improving the luminescence efficiency by reducing a luminous area during a radio frequency discharge.
A further object of the present invention is to provide a radio frequency PDP that is capable of easily implementing a high resolution picture by reducing a luminous area during a radio frequency discharge.
A still further object of the present invention is to provide a method of driving a radio frequency PDP that is capable of reducing a discharge power as well as improving the luminescence efficiency.
In order to achieve these and other objects of the invention, a radio frequency plasma display panel according to one aspect of the present invention includes first and second electrodes, being arranged to be opposed and perpendicular to each other, to generate the radio frequency discharge.
A method of driving a radio frequency plasma display panel according to another aspect of the present invention includes the steps of (A) applying a pulse to each of a scanning electrode and a data electrode crossed with each other to cause an alternating current discharge, thereby selecting cells to be displayed; (B) applying a radio frequency signal to a radio frequency electrode and applying a reference voltage of the radio frequency signal to any one of the scanning electrode and the data electrode, thereby generating a radio frequency discharge at the cells selected at said step (A); and (C) supplying an alternating current pulse to the radio frequency electrode and the electrode to which the reference voltage is applied at a initiation time of the radio frequency discharge to generate a triggering discharge for initiating the radio frequency discharge.